The presently claimed invention relates to a permanent freight securing device to which numerous types of freight securing brace systems may be attached for use in freight enclosures such as highway trailers or intermodal freight containers.
Trailer on flat car (TOFC) and container on flat car (COFC) are high volume and expanding modes of transportation. In such systems, highway tractor trailers and their lading are delivered to a railroad trailer facility where they are placed on specially equipped flat cars and shipped via rail to their destination. Alternately, enclosed containers may be off loaded from highway trailers or ships and placed on flat cars for shipment by rail.
During rail shipment the trailers or containers and the freight loaded therein are subjected to conditions quite different from those encountered in highway movement. The most significant difference is the increased number of longitudinal shocks due to switching of rail cars and/or to slack action within the train. The longitudinal shock forces may shift the lading within the trailer or container causing a significant safety hazard and may result in damage to the trailer or container itself as well as to the freight loaded therein. In particular, damage tends to occur to the end doors of the trailer or container which take the brunt of the forces.
Section II, paragraph 5A of the Association of American Railroads (AAR) Circular 43-A entitled "Rules Governing the Loading, Blocking and Bracing of Freight In Closed Trailers and Containers for TOFC-COFC Service" specifically states that "Trailer doors are not designed to fully restrain longitudinal movement of lading without resulting damage to equipment and lading. Trailer doors may not be used to restrain longitudinal movement of lading, unless specifically permitted by an AAR closed trailer loading publication." Accordingly, additional internal bracing to restrain longitudinal movement of loaded freight is required in trailers or intermodal containers in most instances.
The application of such internal bracing is made difficult by the usual construction of the trailers or containers. Usually, the trailers or containers have weak sidewalls which are constructed of light sheet metal riveted or screwed to vertical wall stiffeners and lined with 1/4 inch thick plywood panels in accordance with AAR specification M-931, paragraphs 5.3 and 5.4. Due to the nature of this construction, fastening internal braces to a trailer or container sidewall by means such as nailing is prohibited by AAR Circular 43-A, Section II, paragraph 5-G.